Animal control systems are useful to control an animal's behavior. Examples include a) containment or exclusion systems to contain an animal within a region such as a yard or to exclude an animal from a region such as a room, food table, sofa, bed or chair, b) training systems to modify the animal's behavior, and c) bark inhibitor systems for dogs. The systems are usually attached to a collar for the animal. A behavior modification signal or correction stimulus is typically an audio sound. A stronger correction stimulus may be an electric shock. While such control systems have been miniaturized as technology has improved, they are still too large and too heavy for a small animal such as a lap dog or small cat. There remains a need for control system circuits that minimize the number of parts and that perform functions in a different mode to permit a reduction in weight and volume.
Animal control has long been accomplished by application of electrical shock. The means for generation of the electrical shock fall into 4 modes.                1 induction coil,        2 alternating current, typically with a step-up transformer,        3 direct current, typically rectified from a step-up transformer and filtered,        4 pulse, typically by capacitor discharge into a pulse transformer.        
All of these approaches are difficult to miniaturize and to effect with limited battery power while maintaining an effective stimulus. The induction coil mode stores energy in the coil's magnetic field, and the energy is delivered by the collapsing inductive field. As the coil is made smaller, less energy can be stored and the shock becomes insufficient to control the animal.
The alternating current mode is limited to low frequencies because the physiological response diminishes with increasing frequency. For a given frequency, as the step-up transformer is made smaller, it is not possible to maintain the necessary primary inductance to keep the transformer core from saturating, which leads to excessive current consumption and diminished output.
The direct current mode stores the energy on a high voltage filter capacitor. Typically the high voltage to be stored on the capacitor is generated by circuitry similar to the alternating current mode just described, except the high voltage is rectified either by half wave, full wave, or voltage multiplier rectification. D.C.-to-D.C. step-up circuits are known for photomultiplier and photoflash circuits. In modern photoflash applications a high frequency is used with a small transformer. A rectifier is used to supply charge to a storage capacitor. If the circuit were to be used in an animal control system, the high voltage storage capacitor would be large and is difficult to miniaturize. The charge may also remain on the capacitor and shock the animal at an inappropriate or unexpected time. Typically a high current is taken from an AA size cell, which is comparatively large and heavy for an animal control system. Further such circuits are not designed for microprocessor control.
The pulse mode uses a pulse transformer with excellent high frequency capability; however, the primary to secondary turns or voltage ratio is limited to low ratios in order to maintain a high self-resonant frequency. As consequence, to achieve high voltages, a high voltage must be supplied to the primary. The high voltage may be supplied by circuitry similar to the direct current mode just described and with the inadequacies just described.
Thus there remains a need for a shock system that can be controlled by a microprocessor, is small and is operable by the limited voltage and current capabilities of a small battery.
Battery powered apparatus that combines low power microprocessors with high power circuits, such as electronic shockers, require power management because the microprocessor may malfunction if the power supply fluctuates excessively. It is well known that the maximum power is obtained from a source when the load is matched. This applies to batteries as well. In a simple matched system the load resistance would be equal to the source resistance, i.e. the internal battery resistance (more correctly when the source and load are conjugate impedances, but considering only the resistance is sufficient in this application). In such a system the terminal voltage of the battery drops to half the open circuit value. Thus a 3-volt battery will drop to 1.5 volts under a matched load. Microprocessors usually fail when the supply voltage drops by half. Also the internal resistance of a battery increases near the end of battery life. Thus, even a load resistance that is higher than the normal battery internal resistance will become significant as the battery nears end of life. To keep the microprocessor from malfunctioning, it is well known to isolate the microprocessor and other circuits from temporary drops in supply voltage by using a diode feeding a capacitor, the latter maintains the voltage supplied to the microprocessor. The typical voltage drop across a silicon diode is 0.7 volts. Even Schottky diodes have 0.3 volts drop or more. This is too much of a voltage drop in a low voltage battery system. For example a fresh 3-volt lithium battery may supply only 2.3–2.7 volts through a diode isolation circuit. This may be insufficient voltage to reliably operate the microprocessor. Batteries also drop in voltage near the end of battery life, and it is desirable to get maximal life from batteries by maintaining operation even at low battery voltages. Voltage losses in load isolation systems thus reduce the amount of useful battery life. While low drop out voltage regulators are available, they do not tolerate an input voltage lower than the load voltage or consume too much power, compromising battery life. The usual protection scheme for the regulator is to use a reverse coupled diode. The strategy is to drag the load voltage down as the supply voltage drops. This protects the regulator but fails to provide the needed isolation.
Thus there remains a need for a power management system that provides isolation from transient supply voltage drops, has a minimal voltage drop and is efficient so as to maintain long battery life.
Animal control systems that are containment or exclusion systems use an electro-magnetic radiated signal from a boundary wire and have a receiving antenna in the form of an unshielded inductor. Such inductors have a solenoidal reception field. Animals can learn to avoid the boundary signal by orienting themselves and, hence, the receiver to the blind spot of the solenoidal field. Simply adding another inductor physically oriented different to the first and paralleling the electrical circuits results in a new reception field that is the vector sum of the two inductors, i.e. another solenoidal field. One solution is to use two or three orthogonal inductors that are activated or switched on singly or in pairs by a controller or microprocessor, as taught in U.S. Pat. No. 5,425,330 and U.S. Pat. No. 5,435,271 to Touchton et al. The inductor or inductor pair having the strongest signal is then selected for further signal processing. This selection process takes time. This lost time diminishes the deterrent effect for those animals that attempt to run through the boundary. Another solution is to sequentially sample or switch on each antenna for a period of time, as taught in U.S. Pat. No. 5,460,124, U.S. Pat. No. 5,682,839, and U.S. Pat. No. 6,269,776 to Grimsley et al. The switching reduces the time the signal can be received, assuming not all three antennas are receiving sufficiently strong signal. This reduces the ability to authenticate a weak signal because some of the antennas, i.e. part of the time, offer insufficient signal to process. The switching also introduces a 0.1 second latency in detecting the boundary signal as it switches through antennas that are not receiving the boundary signal.
Thus there remains a need for an antenna system that is omnidirectional and does not incur the lost time required for selection of the strongest signal or is reduced in ability to authenticate a weak signal or has a detection latency.
Often it is desirable to customize the control parameters of a system for controlling animal behavior. Some systems change characteristics of the transmitter which the receiver detects and modifies the stimulus accordingly. In others systems the receiver is programmed with control parameters, particularly when no transmitter is involved as with bark inhibitors or when multiple animals of differing personality are to be controlled by the same signal or transmitter.
Programming the control parameters in a receiver can be effected by an external magnet and an internal magnetically responsive element, such as a reed switch or a Hall effect device etc. This form of programming is limited to fairly simple control parameters. Complicated control parameters can be programmed by a socket that allows access to the controller as in U.S. Pat. No. 5,435,271. In common all receiver programming access needs to protect the waterproofing of the receiver. The magnet programmer maintains a closed receiver but is limited to simple parameters. The programming socket of U.S. Pat. No. 5,435,271 is waterproof but requires removal of the battery.
Thus there remains a need for programming access that maintains the receiver integrity and allows complicated control parameters.